Build

The Build tab is where the magic happens

FFU Development Path

The FFU Development path ($FFUDevelopmentPath) is the root path of where most other paths are derived. The default is $PSScriptRoot, which is the location the script is currently running from and can be changed to another location from within the UI.

If you want to download and test new releases, or want to create a new FFUDevelopment folder without modifying your existing one, you can always download the source files and put them in another location.

The recommendation is to run from C:\FFUDevelopment and in most cases the path shouldn’t need to be changed.

Custom FFU Name Template

Controls the -CustomFFUNameTemplate parameter. This allows you to define a custom naming convention for the captured FFU file using placeholders that are replaced at build time.

If left blank, the default FFU naming convention is used.

Available Placeholders

Placeholder	Description	Example
{WindowsRelease}	Windows release number	10, 11, 2016, 2019, 2022, 2025
{WindowsVersion}	Windows version	1607, 1809, 21h2, 22h2, 23h2, 24h2
{SKU}	Windows edition	Home, Pro, Enterprise, Education, Standard, Datacenter
{BuildDate}	Month and year	Nov2025
{yyyy}	4-digit year	2025
{MM}	2-digit month	11 (for November)
{dd}	2-digit day	28
{HH}	Hour in 24-hour format	14 (for 2 PM)
{hh}	Hour in 12-hour format	02 (for 2 PM)
{mm}	2-digit minute	09
{tt}	AM/PM designator	AM or PM

Examples

Basic template with date and time:

{WindowsRelease}_{WindowsVersion}_{SKU}_{yyyy}-{MM}-{dd}_{HH}{mm}

Result: Win11_24h2_Pro_2025-11-28_1425.ffu

Template with static text (e.g., indicating Office is installed):

{WindowsRelease}_{WindowsVersion}_{SKU}_Office_{yyyy}-{MM}-{dd}_{HH}{mm}

Result: Win11_24h2_Pro_Office_2025-11-28_1425.ffu

Simple template with build date:

{WindowsRelease}_{WindowsVersion}_{SKU}_{BuildDate}

Result: Win11_24h2_Pro_Nov2025.ffu

Note

The .ffu extension is automatically appended if not included in the template.

FFU Capture Location

The FFU Capture Location sets the -FFUCaptureLocation parameter that determines where completed .ffu images are written. By default it points to $FFUDevelopmentPath\FFU, and the build script creates the folder automatically if it does not already exist.

When apps are installed in a VM, the host converts this folder into a temporary SMB share using the Share Name and Username fields. The capture WinPE environment maps that share as drive W: and streams the captured image directly into this folder. When the build finishes, the share and local account are removed, but the FFU files remain unless a cleanup option deletes them.

Choose a path on fast storage with plenty of free space—the directory must be local to the host running BuildFFUVM.ps1, and large captures can easily exceed 25–30 GB. This location also feeds other options such as Copy Additional FFU Files, Build USB Drive, and Remove FFU, so keeping all finished images here keeps those workflows simple.

Share Name

The Share Name sets the -ShareName parameter that defines the name of the temporary SMB share created during the FFU capture process. The default is FFUCaptureShare.

During the build, the host creates an SMB share that points to the FFU Capture Location and grants access to the temporary local user account defined in Username. The capture WinPE environment maps this share as drive W: using net use and streams the captured FFU image directly to it.

When the build completes, the share is automatically removed along with the temporary user account, leaving only the captured FFU files behind in the FFU Capture Location.

Username

The Username field sets the -Username parameter that BuildFFUVM.ps1 uses when creating the temporary SMB share user. The value becomes a local standard user account that is granted Full Control on the FFU Capture Location share (default C:\FFUDevelopment\FFU) so the capture WinPE session can copy the FFU over net use . The default ffu_user account name works for most scenarios, but you can supply any other local account name that meets your organization’s policies.

When the build starts, the script ensures the account exists, rotates its password to a randomly generated GUID, and grants it access to the share. The Capture WinPE environment maps drive W: with those credentials, then writes the captured image directly into the FFU Capture Location.

After the build finishes, the share is removed and the temporary account is deleted, leaving only the FFU files stored in the capture folder.

Threads

Controls the -Threads parameter, which sets the number of parallel threads used for concurrent operations throughout FFU Builder. The default value is 5.

Operations Affected by Threads

The Threads value applies to the following parallel operations:

Operation	Description
Winget Application Downloads	When downloading multiple Winget applications, each application download runs as a parallel task
BYO Application Copy	When copying multiple Bring Your Own (BYO) applications to the Apps folder, each copy operation runs in parallel
Driver Downloads	When downloading drivers for multiple device models, each driver download and extraction runs as a parallel task

Recommended Values

Threads	Use Case
1	Minimal system impact; useful for troubleshooting or low-resource systems
5	Default; balanced performance for most systems
8-10	Higher concurrency for systems with fast storage and network connections

Note

Setting a higher thread count may improve download times but will increase resource utilization. If you experience stability issues or resource constraints, try reducing the thread count.

Validation

The UI validates that the Threads value is a valid integer greater than or equal to 1. If an invalid value is entered, it automatically resets to 1.

BITS Priority

Controls the -BitsPriority parameter, which determines the priority level for Background Intelligent Transfer Service (BITS) downloads. The default value is Normal.

If you want faster downloads, change the priority to Foreground. Normal priority will significantly slow down downloads since BITS treats non-Foreground downloads as synchronous and queues each download. This means multiple driver or winget application downloads will go much slower than using Foreground. Normal is default as per Microsoft best practice guidance for using BITS.

Build USB Drive

The following sub-options control how the USB drive is created

Allow External Hard Disk Media

Controls the -AllowExternalHardDiskMedia parameter. When checked, allows the use of drives identified as “External hard disk media” via the WMI class Win32_DiskDrive. The default is unchecked.

Most USB thumb drives are identified by Windows as “Removable Media” and work with the default settings. However, faster USB drives—such as portable SSDs or high-speed USB 3.x drives—may be identified as “External hard disk media” instead. If you want to use these faster drives for imaging, enable this option.

Warning

Enabling this option may expose external hard drives attached to your machine to the USB imaging process. To prevent accidental data loss, use the Prompt for External Hard Disk Media option (enabled by default when this option is checked) to confirm which drive to use before formatting.

Prompt for External Hard Disk Media

Controls the -PromptExternalHardDiskMedia parameter. When checked, prompts for user confirmation before using any drive identified as “External hard disk media”. The default is checked when Allow External Hard Disk Media is enabled.

This option is only available when Allow External Hard Disk Media is checked.

When enabled, the build process will:

1. Display a table listing all detected external hard disk media drives, including drive name, serial number, partition style, and status.
2. Prompt you to select which drive to use for imaging.
3. Only create a USB drive on the selected drive.

When disabled, the script will not prompt and can use multiple external hard disk drives simultaneously, similar to how removable USB drives function. This is useful for automated or batch imaging scenarios but increases the risk of accidental data loss.

Note

If you do not want to be prompted each time, you can disable this option after verifying that only your intended imaging drives are connected.

Select Specific USB Drives

When checked, enables manual selection of specific USB drives for imaging. The default is unchecked.

This option is only available when Build USB Drive is checked.

When enabled, a Check USB drives button and a list view appear. Click Check USB drives to scan for connected USB drives. The list displays all detected drives with the following information:

Column	Description
Select	Checkbox to include or exclude the drive from imaging
Model	The model name of the USB drive
Unique ID	A unique identifier for the drive
Size (GB)	The total capacity of the drive in gigabytes

Select one or more drives by checking the checkbox in the Select column. Only selected drives will be formatted and used for imaging when the build completes.

Use the Select All checkbox in the column header to quickly select or deselect all drives.

Note

If Select Specific USB Drives is unchecked, the build process will automatically use all discovered USB drives.

Copy Autopilot Profile

Controls the -CopyAutopilot parameter. When checked, copies the contents of the .\FFUDevelopment\Autopilot folder to the Autopilot folder on the Deployment partition of the USB drive. The default is unchecked.

This option is only available when Build USB Drive is checked.

This leverages the Autopilot for existing devices json file. It’s not recommended to use this method any longer as devices enrolled via this method are enrolled as personal instead of corporate.

Copy Unattend.xml

Controls the -CopyUnattend parameter. When checked, copies the architecture-appropriate unattend XML file from .\FFUDevelopment\Unattend to an Unattend folder on the Deployment partition of the USB drive. The default is unchecked.

This option is only available when Build USB Drive is checked.

When enabled, the build process copies:

• unattend_x64.xml (for x64 builds) or unattend_arm64.xml (for arm64 builds) → renamed to Unattend.xml on the USB drive
• prefixes.txt (if present) → copied alongside the unattend file

During deployment, ApplyFFU.ps1 detects the Unattend folder and uses these files to customize the device name and apply other Windows settings during OOBE.

Device Naming

Device naming can be done from PE. The way this works is by leveraging an unattend.xml file to either take input from the user at imaging time or read a list of prefix values and append the serial number of the device. There are some major benefits to doing this:

1. Total deployment time is reduced if naming is set at FFU deployment time since there is no additional reboot done during OOBE.
2. Reduces the need for multiple provisioning packages or autopilot profiles. This means you can use a single PPKG or autopilot profile.

Prompt for Device Name

If you want to be prompted for the device name, simply check Copy Unattend.xml. This tells the build script to copy the appropriate architecture unattend_arch.xml file from the C:\FFUDevelopment\Unattend folder to the .\unattend folder on the deploy partition of the USB drive.

Device Naming with prefixes.txt

If a prefixes.txt file exists in the Unattend folder and there are multiple prefixes in the file, the deployment script prompts the technician to select a prefix from the file. The prefix is combined with the device’s serial number to create the computer name. If there is a single prefix, the technician is not prompted and the script will automatically select that prefix.

For example, with a prefix of CORP- and a serial number of ABC123, the resulting computer name would be CORP-ABC123 (truncated to 15 characters if necessary).

Sample prefixes.txt content:

CORP-
STORE-
KIOSK-

Warning

If using a provisioning package or autopilot json file, DO NOT specify a name in either of these. They will overwrite the name you have specified in the unattend.xml.

Creating Your Unattend Files

The .\FFUDevelopment\Unattend folder includes sample files you can customize:

File	Description
SampleUnattend_x64.xml	Example unattend file for x64 systems
unattend_x64.xml	Active unattend file used for x64 builds
unattend_arm64.xml	Active unattend file used for arm64 builds
SamplePrefixes.txt	Example prefixes file for device naming

Copy and customize the sample files to create your own unattend_x64.xml, unattend_arm64.xml, and prefixes.txt files.

Note

The unattend file must contain a <ComputerName> element in the Microsoft-Windows-Shell-Setup component for device naming to work. See the sample files for the correct structure.

Copy Provisioning Package

Controls the -CopyPPKG parameter. When checked, copies the contents of the .\FFUDevelopment\PPKG folder to the PPKG folder on the Deployment partition of the USB drive. The default is unchecked.

This option is only available when Build USB Drive is checked.

How It Works

1. During Build: The build process copies all .ppkg files from .\FFUDevelopment\PPKG to the USB drive.
2. During Deployment: When ApplyFFU.ps1 runs, it detects the PPKG folder and the provisioning packages within it.
   • If multiple .ppkg files are found, the technician is prompted to select which package to apply.
   • If one .ppkg file is found, it is automatically selected.
3. Application: The selected provisioning package is copied to the root of the USB drive, where Windows picks it up during OOBE and applies the settings.

Copy Additional FFU Files

Controls the -CopyAdditionalFFUFiles parameter. When checked, allows you to select existing FFU files from the FFU Capture Location to copy to the USB drive alongside the newly built FFU. The default is unchecked.

This option is only available when Build USB Drive is checked.

How It Works

When enabled, an Additional FFU Files panel appears below the checkbox with the following controls:

Control	Description
Refresh	Scans the FFU Capture Location folder for existing .ffu files and populates the list
FFU Name	The filename of the FFU file
Last Modified	The date and time the FFU file was last modified, useful for identifying the most recent builds

The list displays all .ffu files found in the FFU Capture Location (default .\FFUDevelopment\FFU). Click on individual rows to select which FFU files you want to include on the USB drive. Selected files are highlighted in the list.

Use Cases

• Multiple device configurations: Copy different FFU files for different windows/application configurations (e.g., different versions of windows, different application stacks) to a single USB drive, allowing technicians to choose during deployment.
• Previous builds: Include a known-good FFU from a previous build alongside the new build as a fallback option.
• Multi-architecture imaging: Include both x64 and arm64 FFU files on the same USB drive for mixed-architecture environments.

Command Line Usage

When running BuildFFUVM.ps1 from the command line with -CopyAdditionalFFUFiles $true and no -AdditionalFFUFiles parameter specified, the script displays an interactive prompt listing all available FFU files in the capture folder. You can:

• Enter numbers separated by commas (e.g., 1,3,5) to select specific files
• Enter A to select all available files
• Press Enter to skip and not include any additional files

Example command line usage with pre-selected files:

.\BuildFFUVM.ps1 -configFile .\config\FFUConfig.json -CopyAdditionalFFUFiles $true -AdditionalFFUFiles @("C:\FFUDevelopment\FFU\Win11_24h2_Pro_Nov2025.ffu", "C:\FFUDevelopment\FFU\Win11_24h2_Enterprise_Nov2025.ffu")

Note

The newly captured FFU from the current build is always copied to the USB drive. Additional FFU files selected here are copied in addition to the new FFU.

Max USB Drives

Controls the -MaxUSBDrives parameter, which sets the maximum number of USB drives to build in parallel. The default value is 5.

This option is only available when Build USB Drive is checked.

When building USB drives, the script processes multiple drives concurrently to speed up imaging. This setting controls how many drives are formatted and copied to simultaneously.

Compact OS

Controls the -CompactOS parameter. When checked, the Windows image is applied using compressed files. The default is checked.

How It Works

When enabled, the build script uses the -Compact switch with Expand-WindowsImage when applying the Windows image to the OS partition. This compresses Windows system files using Compact OS compression, which reduces the disk footprint of the operating system. On an x64 image, space savings is ~3.5-4GB.

Benefits

Benefit	Description
Reduced Disk Space	Windows files are stored in a compressed state, saving several gigabytes of storage
Smaller FFU Size	The captured FFU file is smaller because the OS partition contains compressed files
Faster Deployment	Smaller FFU files transfer more quickly to USB drives and deploy faster to target devices
No Performance Impact	Modern CPUs decompress files faster than they can be read from storage, so performance is maintained

When to Disable

You may want to disable Compact OS in the following scenarios:

• Windows Server builds: The script automatically disables Compact OS for Windows Server operating systems because the Windows Overlay Filter (wof.sys) is not included in Server SKUs
• Troubleshooting: If you experience issues with specific applications that are incompatible with compressed files
• Maximum performance requirements: In rare cases where every CPU cycle matters

Note

Compact OS is automatically disabled when building Windows Server images, regardless of this setting. The script detects Server operating systems and applies the Windows image without compression.

Update ADK

Controls the -UpdateADK parameter. When checked, the script checks for and installs or updates to the latest Windows ADK and WinPE add-on before starting the build. The default is checked.

How It Works

When enabled, the build process performs the following checks before starting:

1. Version Check: Queries the Microsoft ADK installation page to determine the latest available ADK version
2. Compare Versions: Compares the installed ADK and WinPE add-on versions (if present) against the latest available version
3. Update if Needed: If an older version is detected:
   • Uninstalls the existing Windows ADK
   • Uninstalls the existing WinPE add-on
   • Downloads and installs the latest Windows ADK with Deployment Tools feature
   • Downloads and installs the latest WinPE add-on

Features Installed

When installing or updating the ADK, the following features are included:

Component	Feature ID	Description
Windows Deployment Tools	OptionId.DeploymentTools	Includes DISM, Oscdimg, and other deployment-related tools
WinPE Environment	OptionId.WindowsPreinstallationEnvironment	Windows Preinstallation Environment used for capture and deploy

Installation Location

The ADK is installed to the default location: C:\Program Files (x86)\Windows Kits\10

When to Disable

You may want to disable Update ADK in the following scenarios:

• Offline or air-gapped environments: When internet access is not available to download the latest ADK
• Controlled ADK versions: When you need to maintain a specific ADK version for compatibility or compliance reasons
• Faster builds: When you have already verified you are running the latest ADK version and want to skip the version check

Warning

If Update ADK is disabled and the Windows ADK or WinPE add-on is not installed, the build will fail. Ensure you have manually installed the required components before disabling this option.

Manual ADK Installation

If you prefer to manually install the ADK, visit:

Download and install the Windows ADK

You must install both:

• Windows Assessment and Deployment Kit (with Deployment Tools feature)
• Windows PE add-on for the Windows ADK

Optimize

Controls the -Optimize parameter. When enabled, FFU Builder runs the Windows ADK version of DISM to optimize the captured .ffu file:

• DISM /Optimize-FFU /ImageFile:<path-to-ffu>

This post-processing step typically takes a few minutes and is intended to make FFU images faster to deploy and easier to deploy to differently-sized disks (by allowing the Windows partition to expand or shrink during apply).

Default: Enabled (-Optimize $true)

When to Disable

You may want to disable Optimize (-Optimize $false) if you are troubleshooting, or if you want to skip the extra post-processing time.

Warning

If you plan to deploy the same FFU to devices with different storage sizes (especially smaller disks), keep -Optimize enabled. Non-optimized FFUs are more likely to require additional partition management during deployment.

Note

FFU Builder also performs a separate “optimize VHDX before capture” step. That VHDX optimization is independent of -Optimize, so you may still see “Optimizing VHDX before capture…” even when -Optimize is disabled.

Allow VHDX Caching

Controls the -AllowVHDXCaching parameter. When enabled, FFU Builder caches the base VHDX it creates in $FFUDevelopmentPath\VHDXCache and writes a matching *_config.json file alongside it. On later builds, if a cached VHDX exists that matches your selected Windows settings and update set, the script reuses it to avoid re-applying the base image and integrating updates again.

Default: Disabled (-AllowVHDXCaching $false)

Cache Matching

A cached VHDX is reused only when the cache metadata matches your current build inputs, including:

• Windows release, version, and SKU
• Logical sector size (512 vs 4096)
• Optional features selection
• The exact set of update payload file names downloaded for that run (SSU/CU/.NET/etc.)

Disk Usage and Cleanup

VHDX caching trades disk space for speed. The VHDXCache folder can grow over time as you build different combinations. Periodically check the folder and remove old cached vhdx and config json files as necessary.

Note

To force a full rebuild, delete the contents of $FFUDevelopmentPath\VHDXCache (or disable Allow VHDX Caching) and run the build again.

Create Capture Media

Controls the -CreateCaptureMedia parameter.

When enabled, FFU Builder creates WinPE capture media that is used during VM-based builds (when apps are installed in the VM). FFU Builder attaches this media to the VM and adjusts boot order so the VM can reboot into WinPE and automatically capture the FFU to your FFU Capture Location.

The capture media uses the parameter values from VMHostIPAddress, ShareName, UserName, and CustomFFUNameTemplate and inserts them into CaptureFFU.ps1 which is what is responsible for capturing the FFU from the guest VM to the Host.

Default: Enabled (-CreateCaptureMedia $true)

Note

This option is only relevant when Install Apps is enabled. If Install Apps is enabled, the build forces -CreateCaptureMedia to $true because capture media is required to capture an FFU from the VM.

Tip

If you just need to re-create media, you can use the Create-PEMedia.ps1 script to regenerate the capture or deploy ISO using Create-PEMedia.ps1 -Capture $true or CreatePEMedia.ps1 -Deploy $true.

Create Deployment Media

Controls the -CreateDeploymentMedia parameter.

When enabled, FFU Builder creates WinPE deployment media that is used to deploy an FFU image to a physical device. This media contains the WinPE environment and deployment scripts needed to boot a target machine and apply the FFU image.

The deployment media is saved as an ISO file at $FFUDevelopmentPath\WinPE_FFU_Deploy_x64.iso (or WinPE_FFU_Deploy_arm64.iso for ARM64 builds). This ISO can then be used with the Build USB Drive option to create bootable USB media for physical deployments.

Default: Enabled (-CreateDeploymentMedia $true)

Note

If you only need to capture FFUs from VMs and do not plan to deploy to physical devices, you can disable this option to save time during the build process. However, most scenarios require deployment media for the final step of applying the FFU to target hardware.

Tip

If you just need to re-create media, you can use the Create-PEMedia.ps1 script to regenerate the capture or deploy ISO using Create-PEMedia.ps1 -Capture $true or CreatePEMedia.ps1 -Deploy $true.

Inject Unattend.xml

Controls the -InjectUnattend parameter. When checked, copies the architecture-specific unattend XML file from .\FFUDevelopment\unattend into the Apps ISO so it’s baked into the FFU during the VM build process. The default is unchecked.

This option is only available when Install Apps is checked.

How It Works

When enabled, the build process:

1. Determines the correct unattend file based on the target architecture:
   • unattend_x64.xml for x64 builds
   • unattend_arm64.xml for arm64 builds
2. Creates an Unattend folder inside .\FFUDevelopment\Apps if it doesn’t exist
3. Copies the architecture-specific unattend file to .\FFUDevelopment\Apps\Unattend\Unattend.xml
4. Includes the unattend file in the Apps ISO, making it available to sysprep during the VM build

The unattend file is then used by sysprep during the specialize phase and/or other OOBE phases when the FFU is deployed.

Creating Your Unattend Files

Modify the architecture-specific unattend file in the .\FFUDevelopment\unattend folder:

File	Description
unattend_x64.xml	Unattend file used for x64 builds
unattend_arm64.xml	Unattend file used for arm64 builds

Important

Keep the file names with the architecture suffix (e.g., unattend_x64.xml). The script handles renaming the file to Unattend.xml when copying it to the Apps folder.

When to Use This Option

This option is primarily intended for scenarios where:

• You are not using the USB drive to deploy the FFU and use other deployment methods (e.g., network deployment, disk cloning, etc)
• You want the unattend configuration baked directly into the FFU rather than applied at deployment time

Limitations

Limitation	Description
No prefixes.txt support	Unlike theCopy Unattend option for USB drives, this method does not support prefixes.txt for dynamic device naming based on serial numbers
Fixed configuration	The unattend settings are baked into the FFU at build time and cannot be changed at deployment time
Requires VM to be built	This option only works whenInstall Apps is $true because the unattend file is included in the Apps ISO

Note

Most users should continue using the Copy Unattend option via the USB drive, which provides more flexibility including support for prefixes.txt device naming. Use Inject Unattend.xml only when you won’t be using the USB drive for deployment.

Tip

If you’re using this option, you can disable Build Deploy ISO to save time during the build process since the deployment ISO is not needed when you’re not using the USB drive method.

Verbose

Controls the -Verbose common parameter. When checked, enables detailed verbose output during the build process. The default is unchecked.

In prior builds it was necessary to enable -verbose output to track in real-time the build process if you didn’t have cmtrace.exe or some other log-monitoring tool. With the UI, you can now watch the build in real-time using the monitor tab. Enabling verbose shouldn’t be necessary but is available for those who wish to use it.

Post-Build Cleanup

Cleanup Apps ISO

Controls the -CleanupAppsISO parameter. When checked, the Apps ISO file is automatically deleted after the FFU has been successfully captured. The default is checked.

During the build process, when apps are being installed, the script creates an Apps.iso file in the FFU Development Path (e.g., .\FFUDevelopment\Apps.iso). This ISO contains the contents of the .\FFUDevelopment\Apps folder—including application installers, Office deployment files, and orchestration scripts—and is mounted to the VM during the build to install applications.

When to Disable

You may want to disable Cleanup Apps ISO in the following scenarios:

• Debugging app installations: When troubleshooting application installation issues and you want to manually inspect the ISO contents
• Multiple builds with same apps: If you’re running consecutive builds with identical app configurations and want to reuse the existing ISO to save time (the script will recreate it if missing)
• Archival purposes: When you need to retain a copy of the exact Apps ISO used for a specific FFU build

Note

The Apps ISO is only created when applications are configured for installation. If no apps are being installed in the FFU, this option has no effect. Keeping this option enabled helps conserve disk space by removing temporary build artifacts.

Cleanup Capture ISO

Controls the -CleanupCaptureISO parameter. When checked, the WinPE capture ISO file is automatically deleted after the FFU has been successfully captured. The default is checked.

It’s recommended to keep this checked as each new build re-creates the local username account (e.g. ffu_user) and its password. If you were to retain the capture ISO from a previous build, it’d be using an old password and the capture would fail.

Cleanup Deploy ISO

Controls the -CleanupDeployISO parameter. When checked, the WinPE deployment ISO file is automatically deleted after the FFU has been successfully captured. The default is checked.

During the build process, when Build Deploy ISO is enabled, the script creates a WinPE_FFU_Deploy.iso file (e.g., .\FFUDevelopment\WinPE_FFU_Deploy.iso). This ISO contains a customized Windows PE environment used to deploy captured FFU images to target devices. The deployment ISO is typically copied to a bootable USB drive along with the FFU files for field deployment.

When to Disable

You may want to disable Cleanup Deploy ISO in the following scenarios:

• Creating deployment media separately: When you want to create USB deployment drives at a later time, see USB Imaging Tool Creator for a staged workflow using USBImagingToolCreator.ps1 with a deploy ISO, FFU, and Drivers folder (local path or network share).
• Testing in Hyper-V: When deploying FFU images to Hyper-V VMs for testing, you can attach the deploy ISO directly to a VM as a DVD drive

Cleanup Drivers

Controls the -CleanupDrivers parameter. When checked, the contents of the Drivers folder are automatically deleted after the FFU has been successfully captured. The default is unchecked.

During the build process, when drivers are configured for installation, the script downloads and extracts driver packages into manufacturer-specific subfolders within the Drivers folder (e.g., .\FFUDevelopment\Drivers\HP, .\FFUDevelopment\Drivers\Dell). These drivers are then injected into the FFU during the build.

When to Enable

You may want to enable Cleanup Drivers in the following scenarios:

• Conserving disk space: Driver packages can be large (several gigabytes per manufacturer), and removing them after a successful build frees up storage
• Ensuring fresh drivers: When you want each build to download the latest available drivers rather than reusing previously downloaded versions
• Single-use builds: When building an FFU for a one-time deployment and you don’t need to retain the driver files

When to Disable

You may want to keep Cleanup Drivers disabled in the following scenarios:

• Multiple builds with same drivers: If you’re running consecutive builds targeting the same hardware models, keeping drivers avoids re-downloading them each time
• Debugging driver issues: When troubleshooting driver injection problems and you want to manually inspect the downloaded driver contents
• Offline builds: When building in an environment with limited or no internet access, retaining drivers allows reuse across builds
• Bring Your Own Drivers: When you download and bring your own set of drivers from another source and don’t want FFU Builder to remove them

Note

Only the contents within the Drivers folder are removed—the folder itself is preserved. If no drivers were downloaded during the build, this option has no effect.

Remove FFU

Controls the -RemoveFFU parameter. When checked, all FFU files in the FFU Capture Location are automatically deleted after the build completes successfully. The default is unchecked.

During the build process, the captured FFU image is written to the FFU Capture Location (e.g., .\FFUDevelopment\FFU). This option removes all .ffu files from that folder after the build finishes, including any previously captured FFU files that may exist in the folder.

When to Enable

You may want to enable Remove FFU in the following scenarios:

• USB-only workflow: When you’re using Build USB Drive to copy the FFU directly to a USB drive and don’t need to retain the FFU file on the host machine
• Conserving disk space: FFU files can be very large depending on what you’re installing, and removing them after copying to USB frees up storage
• Automated build pipelines: When running automated builds where the FFU is immediately transferred to another location (such as a network share or deployment server) and no longer needed locally

When to Disable

You may want to keep Remove FFU disabled in the following scenarios:

• Archival purposes: When you want to retain captured FFU images for future deployments or as a backup
• Multiple USB drives: When you need to create additional USB deployment drives at a later time
• Testing and validation: When you want to test the FFU in Hyper-V or other environments before deploying to physical hardware

Warning

This option removes all FFU files in the FFU Capture Location folder, not just the FFU from the current build. If you have previously captured FFU files stored in this folder that you want to keep, do not enable this option or move those files to a different location before building.

Remove Apps Folder Content

Controls the -RemoveApps parameter. When checked, application content in the Apps folder is automatically deleted after the FFU has been successfully captured. The default is unchecked.

During the build process, application content accumulates in several subfolders within the Apps folder (e.g., .\FFUDevelopment\Apps):

Folder	Contents
Win32	Winget source applications and Bring Your Own Apps content copied using theCopy Apps button or manually copied
MSStore	Microsoft Store applications downloaded via Winget
Office	Microsoft 365 Apps installer files downloaded by the Office Deployment Tool

Additionally, the WinGetWin32Apps.json orchestration file in .\FFUDevelopment\Apps\Orchestration is removed. This file is automatically regenerated at build time based on downloaded applications.

When this option is enabled, the cleanup process removes:

• The entire Win32 folder and its contents
• The entire MSStore folder and its contents
• The Office download subfolder (Office\Office) and the setup.exe file within the Office folder

When to Enable

You may want to keep Remove Apps Folder Content enabled in the following scenarios:

• Conserving disk space: Downloaded application installers can consume significant storage, and removing them after a successful build frees up space
• Ensuring fresh downloads: When you want each build to download the latest available application versions rather than reusing previously downloaded content
• Single-use builds: When building an FFU for a one-time deployment and you don’t need to retain the application files

When to Disable

You may want to disable Remove Apps Folder Content in the following scenarios:

• Multiple builds with same apps: If you’re running consecutive builds with identical application configurations, keeping the downloaded content avoids re-downloading applications each time
• Debugging app installations: When troubleshooting application installation issues and you want to manually inspect the downloaded content
• Offline builds: When building in an environment with limited or no internet access, retaining downloaded applications allows reuse across builds
• Preserving Bring Your Own Apps: When you’ve manually copied application content into the Win32 folder and don’t want FFU Builder to remove it

Note

Only the application content subfolders are removed—the Apps folder itself and configuration files such as AppList.json and UserAppList.json are preserved. If no applications were configured for the build, this option has no effect.

Remove Downloaded Update Files

Controls the -RemoveUpdates parameter. When checked, downloaded Windows updates and application update payloads are automatically deleted after the FFU has been successfully captured. The default is unchecked.

During the build process, update files are downloaded to specific locations within the FFUDevelopment folder:

Folder	Contents
KB	Windows Cumulative Updates (CU) and .NET Framework updates
Apps\Defender	Microsoft Defender definition updates
Apps\Edge	Microsoft Edge browser installer
Apps\MSRT	Malicious Software Removal Tool updates
Apps\OneDrive	Microsoft OneDrive installer

When this option is enabled, the cleanup process removes the entire KB folder and the specific update subfolders within the Apps directory.

When to Enable

You may want to keep Remove Downloaded Update Files enabled in the following scenarios:

• Conserving disk space: Windows Cumulative Updates can be several gigabytes in size, and removing them after a successful build frees up significant storage
• Ensuring latest updates: When you want each build to download the absolute latest available updates rather than potentially reusing older cached versions

When to Disable

You may want to disable Remove Downloaded Update Files in the following scenarios:

• Multiple builds: If you’re running consecutive builds, keeping the downloaded updates avoids re-downloading large Cumulative Update files each time
• Offline builds: When building in an environment with limited or no internet access, retaining downloaded updates allows reuse across builds
• Testing and validation: When you want to manually inspect the update files that were included in the build

Note

Only the update-specific subfolders are removed-the Apps folder itself and other application content (unless Remove Apps Folder Content is also selected) are preserved.

Restore Defaults

Use this to restore FFU Builder to its default state. When clicked:

• A confirmation dialog lists what will be removed before anything is deleted.
  • Generated JSON files are removed (config\FFUConfig.json, Apps\AppList.json, Apps\UserAppList.json, Drivers\Drivers.json).
  • Capture, Deploy, and Apps ISO files are deleted.
  • Downloaded artifacts are cleared: Apps payloads (Win32, MSStore, Office downloads), update folders under Apps (Defender, Edge, MSRT, OneDrive), driver downloads, and all .ffu files in the FFU capture folder.
  • UI list views (drivers, apps, Winget search results, AppScript variables) are cleared and all controls are reset to their default values.

Note

VHDX cache and any custom config files in the FFUDevelopment\config folder, and Drivers\DriverMapping.json will remain. DriverMapping.json is retained because you may have made custom changes to it and we want to retain those.

If you want to keep any content prior to restoring defaults, copy it out first.

Save Config File

Saves all current UI selections to a JSON file so you can reload the same settings later or run BuildFFUVM.ps1 from the command line with -configFile (e.g. BuildFFUVM.ps1 -configFile C:\FFUDevelopment\config\FFUConfig.json)

How it works

• Collects the full UI state (paths, toggles, driver/app selections, build options) into a single JSON.
• Defaults the save location to FFUDevelopmentPath\config and suggests FFUConfig.json as the file name. You can browse and pick a different file name or folder.
• Creates the config folder if it does not exist and confirms the save when finished.

Load Config File

Loads a previously saved configuration JSON and repopulates the UI.

How it works

• Click Load Config File to browse for a JSON file (for example, FFUDevelopment\config\FFUConfig.json).
• The UI updates with everything from the file: paths, checkboxes, build options, driver/app selections, and USB settings.
• Supplemental files referenced in the config (Winget AppList.json, BYO UserAppList.json, Drivers.json) are also imported if they exist. Missing helper files are treated as optional and noted for you.
• If the file is empty, unreadable, or invalid JSON, the load is stopped and an error message is shown.

Build FFU

Use Build FFU to run BuildFFUVM.ps1 with the current UI selections.

What happens when you click Build FFU

• The UI gathers all current settings and saves them to FFUDevelopment\config\FFUConfig.json, and launches BuildFFUVM.ps1 -configFile pointing to that file in a background job. FFUConfig.json persists between builds and is read on each opening of BuildFFUVM_UI.ps1 so you can continue where you left off on each new run.
• The window switches to the Monitor tab so you can watch progress in real time.
• The progress bar shows overall completion
• When the job finishes, the button returns to Build FFU and the UI is ready for the next run.

Cancelling a Build

The Build FFU button will change to Cancel while a build is running. Cancelling will do the following:

• The UI stops the background build job and kills any child processes so DISM, downloads, and other tools exit.
• The in-progress download is always removed to avoid partial or corrupt content.
• You’re prompted to decide whether to remove other items downloaded during this run. Selecting Yes removes only this run’s downloads. Any previously downloaded content stays in place.
• When cleanup is finished, the Cancel button reverts to Build FFU and a new build can begin

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